Data converters for transforming signals are used in a variety of ways, for example in electronic circuits.
Data converters are understood to mean devices designed to convert a first signal, which has a first signal format, into a second signal, which has a second signal format. By way of example, an optical signal can be converted into an electronic signal, or vice versa.
Examples of data converters are in particular analog-to-digital converters, which convert an analog signal into a digital signal, and digital-to-analog converters, which convert a digital signal into an analog signal. In many applications, it is necessary and/or useful to perform a calibration of data converters. The aim of such a calibration can be, by way of example, for the conversion of the data to satisfy specific requirements, for example to have a sufficiently linear characteristic. By means of a calibration, it may thus be possible, by way of example, for signals generated by means of a nonlinear data conversion to be linearized by means of a subsequent correction. Such linearization can be performed by means of correction terms, wherein the correction terms can be determined in the context of the calibration. In the case of many data converters, a calibration is carried out once at the factory. In addition, it may be possible for data converters to be calibrated or recalibrated not only at the factory but also during operation, for example by means of suitable calibration methods.
In many applications, a transfer characteristic of the data converter is determined. Such a transfer characteristic describes how an input signal is converted into an output signal by the data converter. A transfer characteristic can change on account of a calibration. Depending on the field of use of the data converter, various requirements may be made in respect of the transfer characteristic. By way of example, for some applications it may be desirable for the transfer characteristic to have a sufficiently linear behavior, that is to say for there to be a linear relationship between the input signal and the output signal over the entire dynamic range of the data converter, or at least in a specific operating range of the data converter.
The transfer characteristic of a data converter may be dependent on design parameters chosen, for example what type of data converter is used and how components are designed. These types of dependencies can be ascertained by means of simulation, laboratory characterization, or by means of automated test equipment (ATE), before the delivery of the data converter. However, the transfer characteristic may also be dependent on further influences which cannot be determined before delivery, for example because there is a dependence on environmental parameters, or because the transfer characteristic changes over time, for example on account of aging processes. For specified operating conditions, a manufacturer usually assures a transfer characteristic in a specific tolerance range, e.g. in the form of a maximum deviation from a linear behavior. Data converters may be subject to aging/degradation processes that can lead to impairment of their characteristic and ultimately to their failure. Data converters can also fail randomly, for example suddenly.